JP2019189472A - Method for producing tube glass and tube glass - Google Patents

Abstract

To improve the quality of the sections of tube glass in a cutting process.SOLUTION: A method for producing a tube glass has a cutting process that includes a laser irradiation step and a stress imparting step. In the laser irradiation step, irradiation start positions SP1-SP4 in a plurality of laser beams L1-L4 are set at different positions in the circumferential direction of a tube glass G1.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a tube glass including a cutting step, and the tube glass.

  For example, a tube glass used for a medical ampoule, a fluorescent tube for illumination, or the like is formed by various methods such as a Danner method or a downdraw method. Hereinafter, the outline will be described by taking the Danner method as an example.

  When producing tube glass by the Danner method, first, molten glass is supplied to a rotatable sleeve disposed in a muffle furnace. The supplied molten glass becomes tubular while being wound around a rotating sleeve. And the tube glass is continuously shape | molded by pulling out the molten glass used as this tube from the front-end | tip of a sleeve with a tube drawing apparatus (traction | pulling apparatus). Thereafter, the formed tube glass (continuous tube glass) is cut to a required length by a cutting device to obtain a tube glass product having a predetermined length (see, for example, Patent Document 1).

  Moreover, as a cutting method of the continuous tube glass, by bringing a cutting blade into contact with the outer peripheral surface of the continuous tube glass that is continuously conveyed, a scratch is formed on the outer peripheral surface, and a thermal shock is applied to the scratch. A method of cutting a continuous tube glass is generally employed (see, for example, Patent Document 2).

  The method disclosed in Patent Document 2 can be cut at a relatively high speed while conveying continuous tube glass, and can be easily incorporated into a production line. However, since the scratch formed on the outer peripheral surface of the continuous tube glass is propagated by thermal shock, it is difficult to stabilize the shape of the scratch that becomes the starting point of the crack. For this reason, the fracture surface (cut surface) of the tube glass becomes rough. Therefore, in the method of the same document, an additional cutting process is required to finish the fractured surface flat, resulting in an increase in man-hours. Moreover, in this method, since the glass powder produced in the cutting process adheres to the inner peripheral surface of the cut tube glass, a cleaning process is also required.

  Patent Document 3 discloses a method capable of preventing the generation of glass powder and cutting the continuous tube glass at a high speed. In this method, laser light is irradiated inside the continuous tube glass, and cracks are generated inside the continuous tube glass due to multiphoton absorption that occurs in the irradiated region. Stress is applied to the continuous tube glass, and cracks develop in the circumferential direction inside the continuous tube glass due to the action of the stress.

  Hereinafter, the laser light irradiation method and the progress of cracks in this cutting method will be described in detail with reference to FIGS. 11 and 12.

  As shown in FIG. 11, the focus F of the laser light L is set inside the continuous tube glass G1 conveyed along the longitudinal direction, and this focus F is an irradiation start position along the circumferential direction of the continuous tube glass G1. The laser beam L is scanned so as to move from the SP to the irradiation end position EP. Thereby, as shown in FIG. 12, the internal crack area | region C1 containing a 1 or several crack is formed in the irradiation area | region of the laser beam L inside the continuous tube glass G1.

  The continuous tube glass G1 is conveyed in a state where a bending force is applied. For this reason, the crack contained in the internal crack area | region C1 progresses in the circumferential direction of the continuous tube glass G1 with the stress provided to the continuous tube glass G1. In FIG. 12, the region where the crack propagates is referred to as “crack propagation region” and is indicated by reference characters C2a and C2b. The crack progress areas C2a and C2b are composed of a first crack progress area C2a that progresses from the irradiation start position SP side and a second crack progress area C2b that progresses from the irradiation end position EP side.

  As shown in FIG. 12, the continuous tube glass G1 is cut when the first crack progress region C2a and the second crack progress region C2b reach the merge position CP opposite to the internal crack region C1 in the radial direction. Is done.

JP2013-159532A JP2013-129546A JP 2017-7926 A

  In the cutting method disclosed in Patent Document 3, a single laser beam L is scanned in one direction from the irradiation start position SP to the irradiation end position EP inside the continuous tube glass G1. In this case, since the range of the internal crack region C1 is short, a shift occurs in the progress direction between the first crack progress region C2a and the second crack progress region C2b, and proceeds from the irradiation start position SP side as shown in FIG. In some cases, the first crack progress region C2a that does not coincide with the second crack progress region C2b that progresses from the irradiation end position EP side at the joining position CP. Therefore, in this method, irregularities (steps) due to mismatch between the crack propagation regions C2a and C2b occur on the cut surface of the continuous tube glass G1, and there is a possibility that the end surface quality of the manufactured tube glass is deteriorated. .

  This invention is made | formed in view of said situation, and makes it a technical subject to improve the quality of the cut surface of the tube glass in a cutting process.

  The present invention is for solving the above-described problems, and includes a cutting step. In the manufacturing method of a tube glass, the cutting step focuses on the inside of the tube glass and starts irradiation with a plurality of laser beams. A laser irradiation step of forming a crack due to multiphoton absorption, and a stress applying step of applying stress to the tube glass so that the crack propagates in a circumferential direction of the tube glass, the laser In the irradiation step, the irradiation start positions of the plurality of laser beams are set to different positions in the circumferential direction of the tube glass.

  As described above, in the present invention, the inside of the tube glass is irradiated with a plurality of laser beams. In this case, by changing the irradiation start position of each laser beam and scanning each laser beam from the irradiation start position, cracks due to multiphoton absorption can be formed in a wide range inside the tube glass. By causing cracks formed over a wide area to progress through the stress application step, the shift in the direction of progress of each crack can be made as small as possible. Thereby, it can prevent that an excessive level | step difference generate | occur | produces in the end surface (cut surface) of the tube glass after a cutting process, and can make the said end surface a high quality thing.

  In the laser irradiation step, it is preferable that the scanning ranges of the plurality of laser beams are set apart in the circumferential direction of the tube glass. When the scanning range of each laser beam overlaps, cracks due to multiphoton absorption are intensively formed in the overlapping part, and the degree of progress of cracks in the circumferential direction and radial direction from the overlapping part However, it can be considered that this is faster than the progress of cracks in other parts (non-overlapping parts). For this reason, in order to reduce the imbalance of the crack progress as much as possible, it is desirable that the scanning ranges of the laser beams as well as the irradiation start positions are separated.

  In the laser irradiation step, it is preferable that the scanning range of each of the plurality of laser beams is set point-symmetrically with respect to the center of the tube glass. By scanning a plurality of laser beams symmetrically with respect to the center of the tube glass, cracks generated in each scanning range can be evenly propagated in the circumferential direction of the tube glass.

  The present invention is for solving the above-mentioned problem, is a tube glass having a plurality of laser irradiation traces on the end face, the sum of the lengths of the plurality of laser irradiation traces in the circumferential direction of the end face, It is 30% or more and 95% or less of the circumferential length of the end face.

  The present invention is for solving the above-described problem, and is a tube glass having a plurality of laser irradiation traces on an end face, wherein the plurality of laser irradiation traces are formed apart from each other in a circumferential direction of the end face. It is characterized by that.

  The present invention is to solve the above-mentioned problems, and is a tube glass having a plurality of laser irradiation traces on the end face, wherein the maximum step of the end face is 500 μm or less.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to improve the quality of the cut surface of the tube glass in a cutting process.

It is a side view of a manufacturing apparatus. It is a side view of a cutting device. It is a front view of an internal crack area | region formation apparatus. It is a perspective view of the continuous tube glass which shows the irradiation aspect of a laser beam. It is a top view of the continuous tube glass which shows the irradiation aspect of a laser beam. It is sectional drawing of the continuous tube glass which shows the scanning aspect of the laser beam from an irradiation start position. It is sectional drawing of the continuous tube glass at the time of irradiating a laser beam to the irradiation end position. It is sectional drawing of the continuous tube glass which shows the process in which a crack progresses. It is the IX-IX sectional view taken on the line of FIG. It is sectional drawing of the tube glass at the time of completion | finish of a cutting process. It is a perspective view of the continuous tube glass which shows the conventional manufacturing method of tube glass. It is sectional drawing of the continuous tube glass which shows the conventional manufacturing method of tube glass. It is the XIII-XIII sectional view taken on the line of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 thru | or FIG. 10 shows one Embodiment of the manufacturing method and manufacturing apparatus of the tube glass which concern on this invention.

  As shown in FIG. 1, the production apparatus 1 forms a continuous tube glass G1 by the Danner method, and cuts the continuous tube glass G1 to produce a tube glass G2 having a predetermined length.

  The manufacturing apparatus 1 includes a glass melting furnace 2, a sleeve 3, a driving device 4 that rotationally drives the sleeve 3, a muffle furnace 5 that accommodates the sleeve 3, an annealer 6, and a tube for drawing a continuous tube glass G <b> 1. It mainly includes a drawing device 7, a cutting device 8 for cutting the continuous tube glass G1, and a transport device 9 for transporting the tube glass G2 obtained by cutting the continuous tube glass G1.

  In this embodiment, the XYZ coordinate system is a fixed-side coordinate system. In this embodiment, a plane including the X axis and the Y axis is a horizontal plane, and a direction along the Z axis is a vertical direction (a positive Z axis). The side is heaven and the negative side is the ground). The xyz coordinate system is a coordinate system on the moving side (coordinate system on the continuous tube glass G1). Like the XYZ coordinate system on the fixed side, the plane including the x axis and the y axis is a horizontal plane and the direction along the z axis. Is the vertical direction.

  The glass melting furnace 2 generates a molten glass M by melting a glass raw material. The glass melting furnace 2 supplies the molten glass M to the upper part of the sleeve 3 in the muffle furnace 5.

  The sleeve 3 is formed in a cylindrical shape by a refractory material. The sleeve 3 is partially tapered, and is arranged so that the small diameter side end portion 3a of the tapered portion faces obliquely downward. The sleeve 3 is connected to the drive device 4 via the shaft 10. The drive device 4 rotates the sleeve 3 to wind the molten glass M supplied onto the sleeve 3 into a cylindrical shape, and draws it into a tubular shape from the small diameter side end 3a.

  The muffle furnace 5 is disposed below the glass melting furnace 2. The muffle furnace 5 is composed of a refractory material. The sleeve 3 is accommodated in the muffle furnace 5. The annealer 6 is disposed on the downstream side of the muffle furnace 5. The annealer 6 gradually cools the molten glass M drawn into a tubular shape. The molten glass M formed into a tubular shape becomes a continuous tube glass G1 by passing through the annealer 6.

  The tube drawing device 7 is disposed on the downstream side of the annealer 6. The tube drawing device 7 pulls the continuous tube glass G <b> 1 that has passed through the annealer 6 at a constant speed and conveys it toward the cutting device 8. The tube drawing device 7 is a continuous tube glass adjusted to have a predetermined outer diameter by pulling in a downstream direction while holding the upper and lower portions of the continuous tube glass G1 with a pair of conveying belts (not shown). G1 is supplied to the cutting device 8.

  The cutting device 8 cuts the continuous tube glass G1 to form a tube glass G2 having a predetermined length dimension. In addition, although the thickness of the tube glass G2 in this embodiment shall be 0.5-2.0 mm, for example, it is not limited to this range.

  As shown in FIGS. 1 to 3, the cutting device 8 is formed by a plurality of internal crack region forming devices 11 a to 11 d that generate cracks inside the continuous tube glass G <b> 1 and the internal crack region forming devices 11 a to 11 d. A crack propagation device 12 for propagating cracks and a support portion 13 that supports the continuous tube glass G1 are provided.

  Each internal crack area | region formation apparatus 11a-11d forms the internal crack area | region C1a-C1d containing one or several cracks as shown in FIG. 6 mentioned later in a part of the circumferential direction of the continuous tube glass G1.

  In this embodiment, although the cutting device 8 provided with the four internal crack area | region formation apparatuses 11a-11d is illustrated, the number of the internal crack area | region formation apparatuses 11a-11d is not limited to this. The internal crack region forming devices 11a to 11d are arranged around the continuous tube glass G1, the first internal crack region forming device 11a, the second internal crack region forming device 11b, the third internal crack region forming device 11c, and the first Four internal crack region forming devices 11d are included.

  The internal crack region forming devices 11a to 11d include laser oscillators (first laser oscillator to fourth laser oscillator) 14a to 14d, output adjustment units (first output adjustment unit to fourth output adjustment unit) 15a to 15d, Scanners (first scanner to fourth scanner) 16a to 16d are individually provided.

  Each of the laser oscillators 14a to 14d emits laser light L1 to L4 (for example, picosecond pulse laser light or sub-picosecond pulse laser light) having a predetermined pulse width toward the output adjustment units 15a to 15d. In the present embodiment, the laser oscillators 14a to 14d emit, for example, green laser light, but the types of the laser lights L1 to L4 are not limited to this.

  Each output adjustment part 15a-15d is comprised by the attenuator (optical attenuator), for example, and has the function to adjust so that the output conditions of each laser beam L1-L4 may become the same.

  The scanners 16a to 16d scan the continuous tube glass G1 with the laser beams L1 to L4 incident via the output adjustment units 15a to 15d. Each of the scanners 16a to 16d is configured by, for example, a galvano scanner, but is not limited to this configuration.

  The crack propagation device 12 causes the continuous tube glass G1 to generate stress that promotes the development of cracks in the internal crack regions C1a to C1d, and propagates the crack over the entire circumference of the continuous tube glass G1.

  As shown in FIG. 2, the crack propagation device 12 includes a bending force application unit 17. The bending force application part 17 includes a plurality of rollers 18 that sandwich the upper part and the lower part of the continuous tube glass G1 in the vertical direction. The position at which the continuous tube glass G1 is supported (clamped) by the plurality of rollers 18 is set to be curved with a predetermined curvature as the central axis X1 of the continuous tube glass G1 goes downstream.

  The support part 13 is comprised by the some roller or roller pair arrange | positioned at predetermined intervals along the longitudinal direction of the continuous tube glass G1 (refer FIG. 1). The support part 13 guides the continuous tube glass G1 drawn out from the annealer 6 to the downstream side in the transport direction (X-axis direction). In FIG. 2, the support 13 is not shown.

  The conveyance device 9 is configured by a belt conveyor or a roller conveyor, but is not limited to this configuration. The conveyance apparatus 9 conveys the tube glass G2 along the direction (for example, Y-axis direction) crossing the conveyance direction (X-axis direction) of the continuous tube glass G1.

  Hereinafter, a method for manufacturing the tube glass G2 using the manufacturing apparatus 1 having the above-described configuration will be described.

  First, as shown in FIG. 1, the molten glass M generated in the glass melting furnace 2 is supplied onto the sleeve 3 that is rotationally driven in the muffle furnace 5. The molten glass M is formed into a tubular shape by the sleeve 3, and then slowly cooled by the annealer 6, and is drawn out from the annealer 6 as a continuous tube glass G <b> 1. The continuous tube glass G1 is sent to the cutting device 8 via the tube drawing device 7. Then, the cutting process which cut | disconnects the continuous tube glass G1 and forms the tube glass G2 with the cutting device 8 is performed.

  In the cutting step, the continuous tube glass G <b> 1 passes between the plurality of rollers 18 related to the bending force application unit 17. At this time, a bending force is applied to the continuous tube glass G1. The continuous tube glass G1 is curved with a predetermined curvature so that the upper side in FIG. 2 is convex. As described above, bending stress is applied to the continuous tube glass G1.

  The laser irradiation process by the internal crack region forming apparatuses 11a to 11d is executed in a state where the bending stress is applied to the continuous tube glass G1 as described above. In the laser irradiation process, the laser beams L1 to L4 emitted from the laser oscillators 14a to 14d are adjusted to the same output conditions (pulse width and output) by the output adjusters 15a to 15d, and then each scanner. Incident on 16a to 16d.

  Each scanner 16a-16d irradiates each laser beam L1-L4 toward the continuous tube glass G1 so that each focus F1-F4 is suitable for irradiation start position SP1-SP4 set inside the continuous tube glass G1. To do.

  Each of the scanners 16a to 16d scans the laser beams L1 to L4 toward the irradiation end positions EP1 to EP4 set in the circumferential direction from the irradiation start positions SP1 to SP4 inside the continuous tube glass G1. To do.

FIG. 3 shows scanning ranges of the laser beams L1 to L4 by the scanners 16a to 16d.
The scanning range of each laser beam L1 to L4 is a range from the irradiation start positions SP1 to SP4 to the irradiation end positions EP1 to EP4. The irradiation start positions SP1 to SP4 of the laser beams L1 to L4 are set at different positions in the circumferential direction of the continuous tube glass G1. In this embodiment, each irradiation start position SP1-SP4 is set so that it may become equal intervals along the circumferential direction of the continuous tube glass G1. Similarly, the irradiation end positions EP1 to EP4 of the laser beams L1 to L4 are set at different positions in the circumferential direction of the continuous tube glass G1. The irradiation end positions EP1 to EP4 are preferably set so as to be equally spaced along the circumferential direction of the continuous tube glass G1.

  In addition, each scanning range of each of the laser beams L1 to L4 is desirably set so as to be point-symmetric with respect to the center of the continuous tube glass G1 (the central axis X1 in a sectional view). That is, it is desirable that the distances from the irradiation start positions SP1 to SP4 to the irradiation end positions EP1 to EP4 are set to be equal. Further, the scanning ranges are spaced at equal intervals in the circumferential direction of the continuous tube glass G1 so as not to overlap each other. When the scanning ranges of the laser beams L1 to 4L overlap, cracks due to multiphoton absorption are intensively formed in the overlapping portion, and the degree of progress of the crack from the overlapping portion is the other portion ( It is conceivable that it becomes faster than the progress of cracks in the non-overlapping portion. For this reason, in order to reduce the imbalance of the crack progress as much as possible, it is desirable that the scanning ranges of the laser beams L1 to 4L as well as the irradiation start positions SP1 to SP4 are separated.

  As shown in FIG. 3, the first laser beam L1 scanned by the first scanner 16a moves the focal point F1 clockwise from the irradiation start position SP1 toward the irradiation end position EP1. The focal point F1 of the first laser beam L1 is scanned so as to draw an arc trajectory along the circumferential direction inside the continuous tube glass G1.

  The second laser light L2 scanned by the second scanner 16b is irradiated so that the focal point F2 is set at the irradiation start position SP2 set at a position away from the irradiation end position EP1 of the first laser light L1. The focal point F2 of the second laser beam L2 is scanned so as to draw an arc trajectory clockwise from the irradiation start position SP2 toward the irradiation end position EP2.

  The third laser light L3 scanned by the third scanner 16c is irradiated so that the focal point F3 is set at the irradiation start position SP3 set at a position away from the irradiation end position EP2 of the second laser light L2. The focal point F3 of the third laser beam L3 is scanned so as to draw an arc trajectory clockwise from the irradiation start position SP3 toward the irradiation end position EP3.

  The fourth laser light L4 scanned by the fourth scanner 16d is irradiated so that the focal point F4 is focused on the irradiation start position SP4 set at a position away from the irradiation end position EP3 of the third laser light L3. The focus F4 of the fourth laser beam L4 is scanned so as to draw an arc trajectory clockwise from the irradiation start position SP4 toward the irradiation end position EP4. The irradiation end position EP4 of the fourth laser beam L4 is set at a position away from the irradiation start position SP1 of the first laser beam L1.

  FIG. 4 shows scanning trajectories of the laser beams L1 to L4 when viewed in a coordinate system (xyz coordinate system shown in the figure) with the continuous tube glass G1 as a reference. Each of the scanners 16a to 16d emits the laser beams L1 to L4 along the circumferential direction of the continuous tube glass G1 so that the virtual sections X2 perpendicular to the central axis X1 of the continuous tube glass G1 include the focal points F1 to F4. Can scan.

  FIG. 5 is a plan view showing scanning trajectories of the first laser beam L1 and the second laser beam L2 when viewed in the XYZ coordinate system with the fixed side as a reference. As shown in the figure, the first laser beam L1 makes an angle θ1 with respect to the central axis X1 while the continuous tube glass G1 moves by a predetermined distance d along the conveyance direction along the central axis X1. Scanning is performed from the irradiation start position SP1 to the irradiation end position EP1 along the direction. Similarly, the second laser light L2 is scanned from the irradiation start position SP2 to the irradiation end position EP2 along a direction that forms an angle θ2 with respect to the central axis X1. It is desirable that the angle θ1 of the first laser beam L1 and the angle θ2 of the second laser beam L2 are set to be equal. Although not shown, the third laser beam L3 and the fourth laser beam L4 are also irradiated from the irradiation start positions SP3 and SP4 at an angle equal to the angle θ1 of the first laser beam L1 and the angle θ2 of the second laser beam L2. Scan to end positions EP3, EP4.

  In the regions irradiated with the laser beams L1 to L4, internal crack regions (first internal crack region to fourth internal crack region) C1a to C1d including one or a plurality of cracks are formed by multiphoton absorption. As shown in FIG. 6, each internal crack area | region C1a-C1d advances to the same direction (clockwise) in the circumferential direction of the continuous tube glass G1 along the scanning direction to each laser beam L1-L4.

  As shown in FIG. 7, when the focal points F1 to F4 move to the irradiation end positions EP1 to EP4, the internal crack region forming devices 11a to 11d end the irradiation of the laser beams L1 to L4. Inside the continuous tube glass G1, a plurality of internal crack regions C1a to C1d having a predetermined length are formed in a strip shape or a line shape spaced apart in the circumferential direction. In this case, it is desirable that the lengths of the internal crack regions C1a to C1d in the circumferential direction of the continuous tube glass G1 are equal to each other.

  Further, in the cutting step, the cracks in the internal crack regions C1a to C1d develop in the circumferential direction and the radial direction by the action of stress acting on the inside of the continuous tube glass G1. Hereinafter, the crack regions C2a to C2d that progress from the internal crack regions C1a to C1d are referred to as “crack progress regions” (first crack progress regions to fourth crack progress regions).

  As shown in FIG. 8, each crack progress area | region C2a-C2d continues expanding at the same speed along the circumferential direction. Finally, each crack progress region C2a-C2d reaches each joining position CP set between each internal crack region C1a-C1d simultaneously. At this time, as shown in FIG. 9, at each merging position CP, the first crack progress region C2a and the second crack progress region C2b coincide with each other without causing a positional shift in the longitudinal direction of the continuous tube glass G1, Or it can merge in the state which made position shift as small as possible. Similarly, the second crack progress region C2b and the third crack progress region C2c, the third crack progress region C2c and the fourth crack progress region C2d, and the fourth crack progress region C2d and the first crack progress region C2a The positions CP can coincide with each other without causing a positional deviation, or can be merged with the positional deviation as small as possible.

  As shown in FIG. 10, when each crack progress area | region C2a-C2d is mutually connected and becomes the connection crack C2, the continuous tube glass G1 will be cut | disconnected. By this cutting, a tube glass G2 having a predetermined length is formed. The manufactured tube glass G2 is sequentially transported in a predetermined direction by the transport device 9 (transport process).

  Internal crack regions C1a to C1d remain as a plurality of laser irradiation marks IM1 to IM4 (see FIG. 10) on the end surface of the manufactured tube glass G2. The plurality of laser irradiation marks IM1 to IM4 are formed at positions spaced from each other at equal intervals so as not to overlap in the circumferential direction of the end face of the tube glass G2. In this case, the sum of the lengths (arc lengths) of the plurality of laser irradiation marks in the circumferential direction of the end surface of the tube glass G2 is 30 to the circumferential length of the end surface (outer peripheral surface) of the tube glass G2. It is preferably 95%, more preferably 50 to 90%.

  According to the method for manufacturing the tube glass G2 according to the present embodiment described above, in the laser irradiation step, the irradiation start positions SP1 to SP4 of the plurality of laser beams L1 to L4 are different positions in the circumferential direction of the continuous tube glass G1. A plurality of internal crack regions C1a to C1d can be formed inside the continuous tube glass G1 by setting (positions separated from each other) and scanning the laser beams L1 to L4 from the irradiation start positions SP1 to SP4. The internal crack regions C1a to C1d are formed on the same plane (on the virtual cross section X2), and the distance between these internal crack regions C1a to C1d is between both ends of the internal crack region formed by scanning with a single laser beam. Therefore, when each crack progresses in the circumferential direction of the continuous tube glass G1, it functions as a guide part that regulates the direction of progress. Therefore, by forming each internal crack region C1a to C1d in a wide range inside the continuous tube glass G1, the direction of crack propagation in each crack propagation region C2a to C2d can be stabilized and the degree of crack propagation can be equalized. . In addition, the cutting process can be performed by reducing the stress applied to the continuous tube glass G1 as much as possible as compared with the case of scanning with a single laser beam.

  The cut surface of the continuous tube glass G1 formed by uniformly extending the crack progress regions C2a to C2d as in the present embodiment has a high quality without a large step. Specifically, the maximum unevenness (maximum step) on the end face of the tube glass G2 can be 500 μm or less.

  In addition, this invention is not limited to the structure of the said embodiment, It is not limited to an above-described effect. The present invention can be variously modified without departing from the gist of the present invention.

  In the above embodiment, the method of manufacturing the tube glass G2 by cutting the continuous tube glass G1 is exemplified. However, the present invention is not limited to this, and the present invention cuts a tube glass of a predetermined length to obtain a plurality of tubes. It is applicable also when manufacturing glass.

  In the above embodiment, the scanning ranges of the laser beams L1 to L4 are separated so as not to overlap, but the present invention is not limited to this, and the scanning ranges of the laser beams L1 to L4 overlap each other. May be set. That is, for example, the irradiation end position EP1 of the first laser beam L1 may be matched with the irradiation start position SP2 of the second laser beam L2.

  In the above embodiment, the cutting device 8 in which the plurality of internal crack region forming devices 11a to 11d are individually provided with the laser oscillators 14a to 14d is illustrated, but the present invention is not limited to this configuration. For example, laser light emitted from one laser oscillator may be split by a splitter, and a plurality of split laser lights may be irradiated into the continuous tube glass G1 by a plurality of scanners.

  In the above-described embodiment, an example in which the focal points F1 to F4 of the laser beams L1 to L4 are scanned so as to draw an arc trajectory is shown, but not limited to this, the focal points F1 to F4 draw a linear trajectory. May be scanned as follows.

  In the above-described embodiment, an example in which a plurality of laser beams L1 to L4 are scanned in the same direction (clockwise) in the cutting step has been described, but the present invention is not limited to this. For example, a part of the laser beams L1 to L4 may be scanned clockwise in the circumferential direction of the continuous tube glass G1, and the other laser beams may be scanned counterclockwise.

F1 focus F2 focus F3 focus F4 focus G1 continuous tube glass G2 tube glass IM1 laser irradiation track IM2 laser irradiation track IM3 laser irradiation track IM4 laser irradiation track L1 first laser beam L2 second laser beam L3 third laser beam L4 fourth laser Light SP1 irradiation start position SP2 irradiation start position SP3 irradiation start position SP4 irradiation start position X1 central axis (center) of continuous tube glass

Claims (6)

In the manufacturing method of a tube glass provided with a cutting process,
The cutting step focuses on the inside of the tube glass, scans a plurality of laser beams from the irradiation start position, forms a crack due to multiphoton absorption, and the crack is in the circumferential direction of the tube glass. A stress applying step of applying stress to the tube glass so as to progress to
In the laser irradiation step, the irradiation start position of the plurality of laser beams is set to a different position in the circumferential direction of the tube glass.   2. The method for manufacturing a tube glass according to claim 1, wherein in the laser irradiation step, a scanning range of each of the plurality of laser beams is set apart in the circumferential direction of the tube glass.   The tube glass manufacturing method according to claim 1 or 2, wherein in the laser irradiation step, a scanning range of each of the plurality of laser beams is set point-symmetrically with respect to a center of the tube glass. A tube glass having a plurality of laser irradiation traces on an end face,
The tube glass, wherein a sum of lengths of the plurality of laser irradiation marks in a circumferential direction of the end face is 30% or more and 95% or less of a circumferential length of the end face. A tube glass having a plurality of laser irradiation traces on an end face,
The tube glass, wherein the plurality of laser irradiation traces are formed apart from each other in a circumferential direction of the end face. A tube glass having a plurality of laser irradiation traces on an end surface,
A tube glass having a maximum step difference of 500 μm or less on the end face.

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